In a communication system, such as a wireless communication system, devices may communicate with one another via an intermediary device. For example, a wireless station and user equipment (UE) may communicate via a repeater. Repeaters may be divided into two types, namely, on-frequency repeaters (OFRs) and frequency translating repeaters (FTRs). An OFR transmits a repeated signal on the same frequency, while a FTR transmits a repeated signal on a different frequency relative to the frequency used when receiving. Thus, OFRs utilize only one frequency resource while FTRs utilize two frequency resources and, as such, lose fifty-percent of those frequency resources. In this regard, the loss of such resources has a negative impact on the data rate or throughput.
A model to evaluate performance and wireless system design is the concept of outage probability. Outage probability is a measure that, in contrast to ergodic capacity, indicates a level of robustness of a wireless link and is defined as Pr{C≦C0}=ε (i.e., the outage capacity C0 that the instantaneous capacity C exceeds with a probability of 1−ε). Outage capacity is typically associated with slow fading channels where the channel remains constant over a number of transmissions. In this regard, outage capacity is concerned with maintaining a constant rate during non-outage periods. In contrast, ergodic capacity is typically associated with fast fading channels where one transmission spans a number of coherence periods and equates to the ensemble average of the information rate. Existing techniques to enhance the outage capacity generally rely on a diversity method (e.g., interleaving, frequency hopping, transmit diversity, or macrodiversity).
Existing repeaters are not designed to reduce the outage capacity experienced by a receiving station. In particular, existing repeaters do not adopt low complexity adaptive schemes that allow for outage capacity optimization and account for different signal strength levels from a repeater, as well as direct path levels from a transmitter. In other words, existing repeaters are not specifically designed to reduce the outage capacity experienced by a receiving station.
WO 2005/064871 A1 relates to relay supported wireless communication to enhance communication performance by using cooperative relaying.